1. Field of the Invention
This invention relates to a heterogenous synthesis reactor. More specifically, the invention relates to a heterogenous synthesis reactor for ammonia, methanol and higher alcohols.
2. Description of the Related Art
Reactors utilizing axial and radial flow through catalyst beds are known in the art. Generally, reaction gases pass through each layer or catalytic bed in a zone with mainly axial flow and in another zone with mainly radial flow. The zone with axial radial flow acts to maintain the catalyst in the catalyst bed cartridge.
U.S. Pat. No. 4,372,920 to Zardi (the present inventor) discloses an axial-radial reactor for heterogenous synthesis using catalyst cartridges. The cartridges have an entirely perforated annular wall and a concentric annular wall with only a minor unperforated portion. Heat exchangers are located within the cartridges with feed gas flowing on the tube side only.
U.S. Pat. No. 4,405,562 to Zardi et al. discloses an axial-radial reactor for heterogenous synthesis which controls the reaction heat by the use of two catalyst cartridges. As in the U.S. Pat. No. 4,372,920 patent, the cartridges also have an entirely perforated annular wall and a concentric annular wall with only a minor unperforated portion. However, only one heat exchanger is used. Furthermore, the feed gas enters from the bottom of the reactor and flows upward to cool the external wall of the reactor's shell and collects in the central duct. The feed gas passes through the exchanger inside the exchanger's tubes, emerging pre-heated in the free zone over the top layer of the catalyst bed where it is mixed with fresh gas.
The reactors of the prior art discussed above provide for temperature control between each bed by means of direct injection of fresh gas or the use of heat exchangers.
Direct injection of fresh gas is achieved by direct admixture between feed gas at a lower temperature and hot gas coming out from each bed of the reactors. However, the conversion efficiency of the reactors is poor because the admixture of the feed gas and the hot gases is not precisely controllable. Also, the use of heat exchangers does not provide for precise temperature control.